Method of preparing it



Patented Aug. 7, 1934 UNrrep STATES 69 I s s ARYL-DIBENZOTHIOQARBOCYANINE AND METHOD or PREPARING rr Leslie. G. S; Brooker, Rochester,

N. Y., assignor to Eastman Kodak Company, Rochester, N. "Y., a corporation of New York No Drawing. Application February 27,1933, Serial No. 658,837

"14 Claims. (Cl. 260-44) This invention relates to dibenzothiocarbocyanine dyes substituted in the 8 position by an aryl or substituted aryl group, and methods for their preparation. These dyes are useful as photographic sensitizers. This application is in part a continuation of my co-pending application Serial No. 520,461, filed March 5, 1931, in which these dyes are described and generically claimed. The instant application is directed more specifically to the dibenzo species of thiocarbocyam'nes. Similarly, these dibenzothiocarbocyanines are described in my Patents Nos. 1,846,301 and 1,846,304, with which my above application Serial No. 520,461,

is to provide dibenzothiocarbocyanine dyes-having aryl, or substituted aryl, substituents attached to the central carbon atom of the three-carbon chain of the dye. A further object of the invention is to provide methods for preparing these dyes. Other objects will hereinafter appear.

These dyes are prepared by condensing a mumethyl naphthothiazo'le, alkyl quaternary salt, i. e. a l-methylaor Z-methyl-e-naphthothia- "zole alkyl quaternary salt-with an ortho-ester of omatic carboxylic acids whichhave been found successful include such esters as triethyl or trimethyl ortho-benzoate and ortho-para-toluate.

. The aromatic acids whose trialkyl ortho-estersare employed may be further described as possessing an aryl group directly linked to the carbon atom may be unsubstituted, as group, or substituted as group. (phenyl) is seen to group (methyl) but for example the phenyl In this latter example the aryl group besubstituted by an alkyl substituents other than a1- kyl groups may be employed, such as for instance;

alkoxy.

The-reaction of a mu-methyl naphthothiazole alkyl 'quaternary salt with one of these orthoesters of-a carboxylic acid, in the presence of a suitable organic base,such-for-exampleas pyriof the carboxyl group. This aryl group for example the pv-tol'yl- :15 was co-pending. These dibenzothiocarbocyadine, may be written graphically as follows-g I l I i i OR! /B o-oH,+R'o- :oR +oH -o +O5H5'N x R x 9 Q }CCH=COH=O 1' +2R"oH+R'oH+o.HiN,'Hx

nines are also referred to inmy co-pending ap- In the above structure Rrrepresents an alkyl plication, Serial No. 435,105, filed March 12, 1930. group and X an acid radical; A stands for the .40 An object of the present invention, therefore, aryl (or substituted aryl) group to, be introduced into the three-carbon chain ofthe thiocarbocy- F lines, or in the 5:6 position, as shown in dotted lines. The dye molecule *is' numbered as shown, so that a compound of this type may be described as a 2:2-dialkyl-8-ary1 (unsubstitutedC r-substituted) dibenzothiocarbocyanine salt. an aromatic carboxylic acid. Ortho-eSters of ar- 'fsuch as the p-toluene-sulionat'e, which confers a comparativelyhigh degree of solubility on the a-methylnaphthothiazole alkyl quaternary can In actual practice it isfrequentlydesi rable to carry out the condensation with an acid radical group and, therefore, the chain CH=CH.CH=*

may be called a tri-methenyl chain, and the chain GH=(IJOH= may similarly be called atrimethenyl chain in.

which the hydrogen attached to the central carbon atom has been replaced by.the group denoted by. the letter A, which is anaryl or substituted aryl group.

The nomenclature and numbering of the above classes of compounds and intermediates are in accord with present usage and also the system used in my co-pending applications given above.

The numbering, of course, is arbitrary and is given for the guidance of those skilled in the art, in order that there be no question as to the identity of a compound covered by my invention.

The m ethods for the preparation of the mumethyl naphthothiazole alkyl quaternary salts aregiven'in the literature and are further ampli- 1 *fied in my Patents Nos. 1,846,300 and 1,846,301. The preparation of the ortho-esters of the'aromatic'carboxylic acids are either described in the literature .or further described in my parent application, Serial No.520,461. a V r a? I will now give several'examples for preparing various dyes referred to, but it will be understood that they are merely representative'of a great number of reactions in which the proportions parent that my invention includes under the term given and equivalents used may vary in accord awith the particular type of dye required. My in- 40 vention, therefore, will not be restricted thereby,

except as indicated in the appended claims.

EXAMPLE I 8-phenyZ-2,2'-dimethyZ-3,4,3',4-dibenaothiocarbocyanine bromide 19.3 parts (2 mols.) of 2- -methyl-.[i-naphthothiazole metho p-toluenesulfonate (prepared by ES condensing the base with methyl p-toluenesulfonate and recrystallizing the product), 11.2

parts (2'mols., i. e. 100% excess) of ethyl ortho-l g... tallized fromi'nethyl alcohol. Thepure dye crys 6 .tallized in minute dull greenish b'rown crystals which dissolved in methyl alcohol with a beautifulviolet-blue coloration. l

7 7 EXAMPLE II 8-phenyZ'-2,2-diethyZ-5,6,5',6'-dibenzothio carbocyanine bromide lioparts, 2 mole.) of l-methyl- -napthothiazole etho-p-toluenesulfonate, 5.6 parts (2 mols.,

.i. e.',100%'excess) of ethyl'ortho-benzoate and 15 parts of pyridine'are boiled under reflux for 30 minutes. The deep blue solution is allowed to .cooland the dye precipitated by adding excess of ether .(100 parts) and-decanting the ethereal layer off. The residue is then dissolved in hot ternary salt used above, the reaction being carbe obtained. .The letter X indicatesany suitable the two benzene rings and that. such substitution 'matic monobasic carboxylic acid having a subdull bluish gray powder, which gives 'a violet- 'blue solution in the solvent.

If 2 mols. of 2-methyl-/3-naphthothiazole ethop-toluenesulfonate are substituted for the quaried out as before, the dye obtained is 8-pheny1- 2,2 diethyl 3,4;3',4' dibenzothiocarbocyanine bromide, whichfdissolves with about the same color in'methyl alcohol.

By substitutingvarious unsubstituted .or substituted aryl groups in the position in the structural formula of the dye occupied by the letter A, and alkayl groups in the two positions occupied by the letter R, many sensitizing dyes may 5 9 anionsuch, for example, as ahalide, p-toluene- Y sulfonate, alkylosulphate, nitrate, acetate, per.- chlorate, or, in fact, any salt forming anion that will not render the dye too sparinglysoluble or deleteriously affectthe photographic sensitizing properties of the dye. 7 It is apparent from a consideration of the above, that the naphthothiazole nucleus may be substituted in the various available positions in comes within'the scope of the appended claims; inasmuch as the preparation of the substituted naphthothiazole quaternary salts are known to those skilled in the art. Furthermore, since I i have described the use of an aryl group as a substituent in the 8-position, and the use of ortho esters of aromatic monobasic acids, it will be ap- (1) an aryl group or (2) an aromatic monobasic carboxylic acid, respectivelyil) both an unsubstituted and a substituted aryl group or (2) an Ti 's aromatic monobasic carboxylic acid having an unsubstituted aryl group directly linked to. the carbon atom of the carboxyl group and an aro- T 20 stituted aryl group linked directly to the carbon atom of the carboxyl group. These substituents in the aryl group may, of course, contain elements other than carbon and hydrogen. While I have described pyridine as the preferred solvent for carrying out this reaction, it will be understood that I may employ any organicbase which is a solvent for the reacting constituents and which also acts to bind acid eliminated by the reaction. M

This organic base should, of course, not suppress the reaction itself. Also, While I have described the reaction as taking place with the greatest efliciency under the influence .of heat, it will be understood that the reaction will take place to a degree even at room temperature, particularly upon long standing. Accordingly, it will be understoodthat the process is not limited to one in which heat must necessarily be employed.

While the principal use now'known for these new chemical compounds isfor sensitizing pho- .tographic emulsions, it may well be that other uses therefor will be discovered from time to time and, consequently, vit'is not intended that the,

reference herein to the sensitizing of these dyes,

.shall, in anyway, limitthe scope of the claims 14:;

appended hereto;

What 'I claim as my invention, and desire to besecured by LettersPatent ofthe United States is:-- r. .1. A 2,2- dialkyl 8-aryldibenzothiocarbocya nine salt the aryl radical being of the benzene series.

2. A 2,2-dialkyl-8-phenyldibenzothi0carbocyanine salt.

3. A 2,2-dialkyl-8-phenyldibenzothiocarbocyanine halide.

4. A 2,2-dialkyl-8-phenyldibenzothiocarbocyanine iodide. v

5. An 8-aryl-2,2'-dialkyl-3.4,3,4'-dibenzothiocarbocyanine salt the aryl radical being of the benzene series.

6. An 8-ary1-2,2'-dialkyl-3,4,3,4'-dibenzothiocarbocyanine halide the aryl radical being of the benzene series.

'7. An 8-aryl-2,2-dialkyl-3,4,3,4-dibenzothiocarbocyanine bromide the aryl radical being of the benzene series. p

8. An 8aryl-2,2-dialky1-5,6,5,6'-dibenzothi0- carbocyanine salt the aryl radical being of the benzene series.

9. An 8-aryl-2,2-dialkyl-5,6,5,6-dibenzothiocarbocyanine halide the aryl radical being of the benzene series.

10. An 8-aryl-2,2-dialkyl-5,6,5',6-dibenzothiocarbocyanine bromide the aryl radical being of the benzene series.

11 The process of preparing dibenzothiccarbocyanines which comprises condensing a mumethyl-naphthothiazole alkyl quaternary salt with a trialkyl ortho-ester of an aromatic monobasic carboxylic acid of the benzene series in the presence 10f an organic base which is a solvent for the reacting constituents and acts to bind acid eliminated from the quaternary salt as a result of the condensation.

12. The process of preparing dibenzothiocar bocyanines which comprises condensing, under the influence of heat, a mu-methyl-naphthothiazole alkyl quaternary salt with a trialkyl orthoester of an aromatic monobasic carboxylic acid of the benzene series in the presence of an organic base which is a solvent for the reacting constituents and acts to bind acid eliminated from the quaternary salt as a result of the condensation.

13. The process of preparing dibenzothiocarbocyanines which comprises condensing a mumethyl-naphthothiazole alkyl quaternary salt with a trialkyl ortho-ester of benzoic acid in the presence of pyridine.

14. The process of preparing dibenzothiocarbocyanines which comprises condensing a mumethyl-naphthothiazole alkyl quaternary salt with triethyl-ortho-benzoate in the presence of pyridine.

LESLIE G. S. BROQKER... 

